The present disclosure relates to processes for producing uniform grain size hot-worked Cu—Ni—Sn spinodal alloys. Generally, the process may be used for creating spinodal alloys of uniform grain size without undergoing a homogenization step and without cracking. In lieu of a homogenization step, as-cast metal alloys are subject to particular heat treatment steps to produce spinodal alloys of uniform grain size.
Processes for creating metal alloys of uniform grain size traditionally include a homogenization step combined with other heat treatment and/or cold working steps. Homogenization is a generic term generally used to describe a heat treatment designed to correct microscopic deficiencies in the distribution of solute elements and modification of intermetallic structures present at the interfaces. One acceptable result of the homogenization process is that the elemental distribution of an as-cast metal becomes more uniform. Another result includes the formation of large intermetallic particles which form during casting and may be fractured and removed during heat-up.
Homogenization procedures are normally required prior to performing cold rolling or other hot working procedures in order to convert a metal into a more usable form and/or to improve the final properties of the rolled product. Homogenization is carried out to equilibrate microscopic concentration gradients. Homogenization is normally performed by heating the casting to an elevated temperature (above a transition temperature, typically near its melting point) for a few hours up to several days, with no mechanical working performed on the casting, and then cooling back to ambient temperature.
The need for the homogenization step is the result of microstructure deficiencies found in the cast product resulting from early stages or final stages of solidification. Such deficiencies include non-uniform grain size and chemical segregation. Post-solidification cracks are caused by macroscopic stresses that develop during casting, which cause cracks to form in a trans-granular manner before solidification is complete. Pre-solidification cracks are also caused by macroscopic stresses that develop during casting.
Traditional processes of producing uniform grain size have recognized limitations. Primarily, they generally require a homogenization step, which can cause unneeded macroscopic stresses that promote cracking.
It would be desirable to provide processes for generating spinodal alloys of uniform grain size without performing a homogenization step. Such methods would be would be advantageous as they lessen the chance for macroscopic stresses and cracking to occur in spinodal alloys.